"The army's role will evolve, but the whole process might take as long as 30 to 40 years. There is absolutely no chance of Nato pulling out." So says Sir David Richards, the new head of the army.

He cannot mean that British soldiers will still be engaged in fighting the Taliban in 30 or 40 years' time. More likely, he means that Britain, and British officials, if not armed troops patrolling the towns and villages, will then be in Afghanistan engaged in civil projects – economic, societal, administrative.

Richards, like Gen Sir Richard Dannatt, his predecessor who stands down at the end of this month, believes, in common with US defence chiefs, that more forces are needed now to fight the Taliban. He also knows that the message that must get out – to all Afghans as well as the Taliban – is that foreign forces won't leave them in the lurch.

Britain is involved in a war in Afghanistan, he says, echoing warnings expressed recently by Dannatt. But it is a multi-faceted conflict. "It will take time," he told the Times newspaper in an interview. He added: "This is nation-building – not the starry-eyed type, but nation-building nonetheless. It is not just reconstruction; jobs and simple governance that works are key, and there has to be a strong reconciliation element to the latter." It is in that context that he spoke of the process taking up to 40 years.

Richards is no stranger to Afghanistan. He was head of the Nato-led international security assistance force, Isaf, in 2006. In that role, he was already trying to work with tribal leaders.

"The country and its people have entered my bloodstream," he told me earlier this year when I interviewed him for The Great Game, a series of plays and verbatim interviews at London's Tricycle Theatre.

He added: "It's the people, with their exotic blend of great kindness through to terrifying savagery, and everything else in between, that makes this country so fascinating, almost intoxicating, to the outsider. It is a place that historically has lured adventurer and intellectual alike and, misunderstood, has been the cause of many a great nation's military catastrophe."

He continued: "And do not forget that these people, in and since inflicting the last of these defeats – on the Soviet Union - have been through hell and back over two complete generations. This, their reward for playing a key role in the collapse of communism and the liberation of hundreds of millions of people in eastern Europe; something for which they got precious little credit then or since."

Richards said the Taliban ranged from hardline militant Islamists through to drug barons and alienated tribal chiefs, but composed a very small part of the population; probably around 5% at most and they are all from one ethnic group.

Military commanders repeatedly say there is no military solution to the conflict. They have been pulling their hair out at what they regard as the failure of others – including other British government departments such as the Foreign Office and Department for International Development – to get a grip and contribute to a settlement, if not a solution, in Afghanistan.

The message appears to be getting across. But there are likely to be many more military deaths before we will be able to tell the difference.